Processes for producing organic amines have been known in the art for quite some time. For example, U.S. Pat. No. 3,994,975 relates to the reductive amination of unsaturated cyclic ketones; to cyclic amines prepared thereby; and to uses thereof. For example, when isophorone is reductively aminated, trimethyl cyclohexylamines and cyclohexenamines are obtained. The invention includes uses of the amine products as fuel additives for stabilizing distillate fuels.
U.S. Pat. No. 4,521,624 provides a process for the reductive amination of a saturated cyclic ketone which comprises reacting a saturated ketone with an amine in the presence of hydrogen and a hydrogenation catalyst, whereby said saturated cyclic ketone is converted to the corresponding cyclic amine.
U.S. Pat. No. 5,001,267 relates to secondary alkyl amine derivatives of ethylenediamine which are formed in a one-step reaction when ethylenediamine is substantially simultaneously continuously mixed with a methyl alkyl ketone to form a reaction mixture which is continuously hydrogenated in the presence of a hydrogenation catalyst and hydrogen. The alkyl group contains 1 to 4 carbon atoms.
U.S. Pat. No. 5,093,528 teaches a process for producing a secondary amine terminated polyether from a primary amine terminated polyether in which the primary amine terminated polyether is reacted at elevated temperature with a carbonyl compound in the presence of hydrogen and a catalyst composition comprising nickel, ruthenium and at least one other transition metal selected from the second or third row transition metals. The amount of carbonyl compound employed is in excess of the stoichiometric amount required to react completely with the ether. The secondary amine terminated polyethers are useful in the formation of polyurea elastomers.
While the prior art is replete with descriptions of processes for producing organic amines, there has been no work concerned with producing secondary amines selectively, for example, secondary amines derived from isophorone diamine using acetone in the presence of hydrogen and a catalyst to form secondary amines. When base metal catalysts (Ni, Co, etc.) are used, a high acetone to amine ratio is required and even under these conditions a low conversion to amine is observed. Also, amine dimer (amine coupling product) is formed in substantial amounts.